Ammunition



Oct. 21, 1941. H. N. MARSH ET AL 2,260,257

AMMUNITION Filed May 12, 1959 HENRY N. MARSH LEWIS C. WELDIN INVENTORS.

ATTORNEY.

BY M h. Man-Mg.

Patented Oct. 21,1941

smmm'nox Henry N.

Marsh, Wilmington, Del., and Lewis 0.

Weldin, Kenvil, N. J., assignors ,to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application May 12, 1939, Serial No. 273,212

Ciaims.

This invention relates to improved loaded cartridges for, firearms and more particularly to loaded cartridges of the rim-fire type for use in small caliber rifles.

The art has long produced cartridges for small caliber rifles which give a relatively slow bullet velocity without a great deal of difficulty. When the trade demanded that small caliber rifles of the'.22 caliber type be supplied with high velocity cartridges, the art experienced trouble in producing satisfactory devices. Production of high velocity cartridges was difllcult due to various limiting factors such as, for example, the small volume of the .22 cartridge case, which limited the amount of powder that could be used; the lack of uniformity in the construction oi the breech of the various commercial .22 rifles; the requirement of chambering .22 rifles to accommodate "short," "long, and long rifle" cartridges; the

variation and lack of strength of the various metal parts of the .22 rifle; and the possibility of the cartridge casing rupturing under the increased pressures us'ed to obtain the higher v'elocities.

Of the .above mentioned manufacturing difli- .culties encountered with .22 caliber components those dealing with the construction of the rifle have been overcome. The other difllcultles have not been overcome as it has not been found desirable to increase the volume of the cartridges and it has been found impossible to increase the strength of the cartridges because since cartridges used in .22 caliber rifles are of the rimfire type, that is having the priming composition distributed within the recess formed by the up- 'etting operation, the strengthening of the carridge by increase of metal thickness restricts the priming composition space unduly. Therefore,

due to the impossibility or undesirability of increasing the volume and strength of the cartridge 'case it has been necessary to obtain the required ballistics by variation of the propellant powder charges used. Now an increase in the velocity of rifle bullets is usually accomplished by increasing the weight of the powder charge or by using a powder which will develop higher pressures" in the cartridge; As the size of the .22 caliber cartridges prevents the increase of the powder charge and the strength of the cartridge prevents the use of higher pressures, the art has surface modified propellant powders to give progressive burning characteristic to the powder that will provide the ballistics necessary to give the high velocities wanted and will also keep the.

pressures developed at a value which will. not rupture. the cartridge case. To accomplish the desired results, the art surface modifies the powder by coating the individual-powder grains with various compounds such as, for example, di-- amylphthalate, diethylphthalate, dinltrotoluene diethyldiphenylurea, or other substances well known to those skilled in the art. With modified,

powders, when ignited by the priming composition, the initial combustion rate is retarded and the overall burning of the charge is progressive and, therefore, a progressive force is exerted upon the bullet which develops the high velocities desired without developing excessive pressure within the cartridge casing.

While the useof surface modified powders has been considered successful in the production of high velocity bullets, there are attending disad-. I

vantages in their manufacture and use. The manufacture of surface modified powders necessitates a coating operation whichv adds about three days to the manufacturing period, thus increasing the cost proportionally; further, the actual coating procedure is dangerous due to the additional handling of the powder required and the explosive vapor hazard that may be created when the coating material is applied by using a solvent.

The use of surface modified powders necessitates strict control over the priming compositionused in the cartridges to be loaded as ignition of surface modified powders is quite often. difficult. The diiflculty of igniting surface modified powders effects the accuracy of the bullets and causes wider variations in velocities and chamber pressures than are desired. Although the use of surface modified powder has the disadvantages discussed hereinbefore the art has not been able to produce an .unmodified powder which is considered suitable for use in high velocity small caliber rifles and have, in fact, considered that surface modification is absolutely necessary to obtain suitable powders. The use of surface modified powders in small caliber rifle cartridges is set forth in U.S. Patent 2,106,107 and this patent further points out that surface modification is considered essential by the art to obtain the proper ballistics in high velocity .22 rifle components. I

This invention has as anobiect the production of a propellant powder charge for high velocity small caliber rifles. A further object of this invention is the production of a propellant powder adapted for use in a .22 caliber cartridge and which is not surface, modified. A still further object of this invention is the production of a loaded cartridge for use in .22 caliber rifles which will give a high bullet velocity with a safe breech pressure. Other objects will appearhereinafter.

Having now indicated in a general way the nature and purpose of this invention there follows a more detailed description of the preferred embodiments thereof, with reference to the aceompanying drawing in which the single figure indicates with parts in cross-section a rim-fire cartridge.

. the ballistics that are required for high velocity in accordance with this invention and, in the In the single'fls'ure the cartridge includes a metallic casing I. usually of bronze or copper which has a lead or similar bullet I inserted and clamped into its open end. The breech end of the cartridge contains a priming compoution I which usually consists of a detonating material and an abrasive material. This priming composition is positioned within the annular space formed when the cartridge is upset. In the cartridge casing I there is a charge of smokeless powder of the type which we have found useful composition: ton-83.75%, diphenylamine.75%, and potasshown below in Table 1 with comparative re-' suits obtained from modified powders. The powder grains have approximately the following nitroglycerin-15.00%, nitrocotslum nitrate-50%; and each sample was tested in the same components and in the same test gun. The components used were Remington long rifle shells with a 40 grain lead bullet and these assembled cartridges were fired in a Winchester V 8: P Gun having e24 inch barrel.

Table 1 Powder Chrg. Pressure 52 Length Dis.

.8! col. surface modified Gmhu l/Iq. in. Grains Example! 2.18 1,378 8,31) .038 .0080 .030? Example 2 200 1, 377 24, 5(1) 038 (X151 0312 Example 4.." 111 am 23,000 .osa .0013 .0205 Enmpied 2.27 1,378 22,000 .045 .0177 .0300 'Exnmple0 1.90 1,381 22,210 .038 .oocs .0293 Exam 2.04 1,877 23,600 ,045 .M! .0350 Emmple8-. 207 1,381 22,2 .06) mos .0450 pie 2 10 1, 377 23, 310 063 0427 l 2% diethyl thaiate eoatin 1 1X95 diethgfphthalate in our invention. The powder consists of flakes 4 which are of predetermined diameter and length. In general the flakes will be cylindrical. The powder used in accordance with this invention is not coated.

Now in accordance with this invention there has been produced a double base smokeless powder that need not be surface modified to give small caliber rifle bullets. Thus, although the arthas been unable to produce suitable ballistics for high velocity small caliber rifies, such as .22 caliber rifles, without surface modification of'the powder used, it has. been found that in accordance with this invention .22 caliber components may'be assembled with a charge 'of uncoated double base smokeless powder which will give suitable ballistics.- The double base smokeless powder used, in accordance with this invention,

in the .22 caliber rifie' components has a granulation which is relatively very much larger'than the usual granulations used in .22 caliber rifies. Thus, by controlling the granulation of a double base smokeless powder, ballistics equal to those obtained with surface modified powders have been obtained. The art uses a surface modified grain that is approximately .03 inchin diameter and between .004 and .005 .inch in length while face of accepted practices, grains with a diameter or from about .02 to .05 inch and'with a length of from about .006 to .0085 inch have beenused to load -.22 caliber cartridges. By the use of thelarge unmodified powder grains, .22 caliber cartridges may be produced that have a muzzle velocity of about 1,375 feet per second and a breech pressure of about 24,000 pounds 1 per square inch, with standard weight charges.

Specific embodiments of this invention are 85 In the above table, Examples 1 and '2 were fired to obtain the standard high velocity bullet muzzle velocity oi 1,375 feet per second and the pressure developed with the necessary charge of. 2.00 to 2.13 grains of powder is normal at about 24,000 to 24,500 pounds per square inch. v The Examples 4 to 9 are powders prepared in accordance with this invention and were fired similarly to Examples 1 and 2, that is, to obtain a velocity of 1,375 feet per second. The results show that this velocity was obtained with approximately the same weight powder charges and Pressures. Thus, the charge weight varied from 1.96 to 2.27 grains and the pressures developedwere in every case below 24,000 pounds per square inch.

Because of the very small surface of the edges of the powder grains in comparison with the face 01 the grain, the diameter of the grain makes 45 but little difi'erence in the resulting ballistics. A diameter larger than .035. inch is apt, to cause difiiculty because of the un-uniform charging in the loading plate and a grain smaller than about .028 inch is difiicult to manufacture so we prefer a grain between .028 inch and .025 inch. A length of grain smaller than .006 inch would give too high a burning rate and for some loading a longer grain is preferred. Increasing the length of grain over .0085 inch does not materially increase the velocity obtainable so we prefer our powder grain to have a length of between .006 inch and .0085 inch. Further increase in grain .length increases the charge weight required and for economic reasons this is'not desirable.

A modification of the grain structure by perforation was also found to give satisfactory ballistics provided the grain diameter was controlled. The results of two perforated powders in the components used in Table 1 and shot for comparison with Examples 1 and 2 a: Table 1 are given below.

Ta le2 "ram: cm. 355,: m 5:. Pin 1mm Dis. 3;;

Enmpleu. 1,115 ""136 our on ones cm was Eramplellaoo 1.1m 'aoo .oco I020 I000: Iowa Iowa I From the above results it is noted that in accordance 'with this invention high velocity cartridges, may also be produced with perforated grains of controlled granulation, that give pressures below 24,000 pounds per sq. in.

In the above examples, powder of a single composition has been used but a further modification of this invention may be made in the use of powders of different compositions. Thus, to illustrate the alternative powder compositions, the following two examples are given which upon testing in regard to pressure and velocity give results which are comparable to the powders given in the previous tables.

Example 14 Composition 40% nitroglycerine, 59.25% nitrocotton 01' 13.25 nitrogen, and 0.15% centralite (diethyldiphenylurea) length at grain .0065 inch, diameter of grain .038 inch; weight oi charge 2.03 grains; muzzle velocity 1,371, feet per second; pressure 24,800 poundsper square inch.

Example 15 Composition 40% nitroglycerine, 59.25% nitrocotton containing 12.92% nitrogen, 0.75% centralite; length of grain .0064 inch, diameter of grain .038 inch; weight of charge 2.05 grains;

.mullzle velocity 1,380 feet per second; pressure material required with modified powder.

23,000 pounds per square inch.

Thu.s, from the above results, it is noted that in accordance with this invention the compositions of the powder grains may vary widely but, by the proper control of the granulations, the velocities and pressures desired may be obtained without recourse to surface modification of the individual grains.

The advantages of using unmodified powders in .22 caliber high velocity cartridges will be aptridges produced in accordance with this invention also give ballistics that show less variation in velocity and pressure than cartridges loaded with the modified powders now used by' the art.

It will be understood that the details and examples given hereinbeiore are illustrative only and in no way limiting on our invention as broadly described hereinbefore and in the appended claims.

What we claim and desire to protect by Letters Patent is:

1. A loaded .22 caliberrim-flre rifle cartridge comprising a shell having a primer recess formed at its rim, a priming composition therein, a prol5 Jectile and a double base smokeless powder charge of unmodified cylindrical grains having a diameter within the range of .02! to .05 inch and a length within the range of .006 to .0085 men.

2. A loaded .22 caliber rim-fire rifle cartridge comprising 'a shell having a primer recess iormed at its rim, 8. priming composition therein, a prolectile, and a double base smokeless powder charge of unmodified cylindrical grains having a diameter of about .03 inch and a length of about .0065 inch.

3. In combination with a .22 caliber rim-fire rifie cartridge, a propellant charge consisting of cylindrical double base smokeless'powder grains without surface modification and at least .005

inch in length and having a diameter not greater than about .05 inch.

4. A lbaded .22 caliber rim-fire rifie cartridge comprising a shell having a primer recess formed at its rim, 2. priming composition therein, a projectile and 'a nitrocellulcse-nitroglycerine powder charge consisting of cylindrical grains without surface-modification, said grains being about .006 to about .0085 inch in length and having a diameter between about .02 and about .05 inch.

5. A loaded .22 caliber rim-fire rifle cartridge comprising a shell having a primer recess formed at its rim, a priming composition therein, a pro- Jectile, and a nitrocellulose-nitroglycerine perfor'ated powder charge consisting of cylindrical grains without surface modification, said grains being about .006 to about .0085 inchin length and having a diameter between about .02 and about .05 inch.

HENRY N. MARSH. LEWIS C. WELDIN. 

